[OVN] Add baremetal support without Neutron DHCP agent for IPv4

This patch adds support for deploying baremetal nodes with OVN's
built-in DHCP server for IPv4.

Since Neutron API's for setting DHCP options is mostly a pass-thru,
Ironic uses a dnsmasq syntax for setting the baremetal options [0].
Since this syntax is unlikely to change and it's only a tiny subset of
what dnsmasq can offer this patch does translate that syntax used by
Ironic and convert it to OVN's equivalent options. In this way we do not
need to re-design Neutron's DHCP options API nor change Ironic to use it
with ML2/OVN.

This option also adds a new configuration option called
"disable_ovn_dhcp_for_baremetal_ports". PXE booting nodes can be very
sensitive and operators may prefer to use a fully-fledged DHCP server to
do it (even Ironic makes DHCP pluggable). So if operators wish to
disable OVN's built-in DHCP server for baremetal provisioning they can
do so by setting this new option to True. It defaults to False.

This change has been tested with real hardware and it does work. That
said, we found a problem in core OVN itself [1] while testing it that
can affect PXE from reaching the TFTP server, we already communicated
this with the core OVN folks and we hope it can be fixed soon. The
change in core OVN should not affect the Neutron change tho.

Not that the "server-ip-address" DHCP Option now points to the
"next_server" option in OVN instead of the "tftp_server_address". The
previous behavior was wrong, the "server-ip-address" should set the
"siaddr" in the DHCP header and this has been introduced in OVN [2] as
an option called "next_server".

[0]
49113385e8/ironic/common/pxe_utils.py (L523-L538)
[1]
https://mail.openvswitch.org/pipermail/ovs-discuss/2022-May/051821.html
[2]
https://patchwork.ozlabs.org/project/ovn/patch/20220511142757.168196-1-lmartins@redhat.com/

Partial-Bug: #1971431
Change-Id: Ia041f640293ba26abf9f70af915817e9861e8ffc
Signed-off-by: Lucas Alvares Gomes <lucasagomes@gmail.com>
This commit is contained in:
Lucas Alvares Gomes 2022-05-03 14:37:46 +01:00
parent 9ca5c1cc04
commit e73a85f3dd
9 changed files with 259 additions and 53 deletions

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@ -20,24 +20,25 @@ at [1]_.
can announce host routes for both floating and fixed IP addresses. These
functions are not supported in OVN.
* Baremetal provisioning with iPXE
* Baremetal provisioning with iPXE without Neutron DHCP agent for IPv6
The core OVN DHCP server implementation does not have support for
sending different boot options based on the ``gpxe`` DHCP Option
(no. 175). Also, Ironic uses dnsmasq syntax when configuring the DHCP
options for Neutron [4]_ which is not understood by the OVN driver.
Work on that is in progress currently, see [5]_ and [6]_.
The core OVN built-in DHCP server implementation does not
yet support PXE booting for IPv6. This can be achieved at
the moment if used with the Neutron DHCP agent by deploying it
on OVN gateway nodes and disabling the OVN DHCP by setting the
``[ovn]/disable_ovn_dhcp_for_baremetal_ports`` configuration option
to True.
* QoS minimum bandwidth allocation in Placement API
ML2/OVN integration with the Nova placement API to provide guaranteed
minimum bandwidth for ports [7]_. Work in progress, see [8]_
minimum bandwidth for ports [4]_. Work in progress, see [5]_
* IPv6 Prefix Delegation
Currently ML2/OVN doesn't implement IPv6 prefix delegation. OVN logical
routers have this capability implemented in [9]_ and we have an open RFE to
fill this gap [10]_.
routers have this capability implemented in [6]_ and we have an open RFE to
fill this gap [7]_.
* East/West Fragmentation
@ -51,12 +52,12 @@ at [1]_.
from instances to reach the DHCP agent. For OVN this traffic has to be explicitly
allowed by security group rules attached to the instance. Note that the default
security group does allow all outgoing traffic, so this only becomes relevant
when using custom security groups [11]_. Proposed patch is [12]_ but it
when using custom security groups [8]_. Proposed patch is [9]_ but it
needs to be revived and updated.
* DNS resolution for instances
OVN cannot use the host's networking for DNS resolution, so Case 2b in [13]_ can
OVN cannot use the host's networking for DNS resolution, so Case 2b in [10]_ can
only be used when additional DHCP agents are deployed. For Case 2a a different
configuration option has to be used in ``ml2_conf.ini``::
@ -69,13 +70,10 @@ References
.. [1] https://github.com/ovn-org/ovn/blob/master/TODO.rst
.. [2] https://bugzilla.redhat.com/show_bug.cgi?id=2060310
.. [3] https://review.opendev.org/c/openstack/neutron/+/842292
.. [4] https://github.com/openstack/ironic/blob/123cb22c731f93d0c608d791b41e05884fe18c04/ironic/common/pxe_utils.py#L447-L462>
.. [5] https://review.opendev.org/c/openstack/neutron/+/840287
.. [6] https://review.opendev.org/c/openstack/neutron/+/840316
.. [7] https://specs.openstack.org/openstack/neutron-specs/specs/rocky/minimum-bandwidth-allocation-placement-api.html
.. [8] https://review.opendev.org/c/openstack/neutron/+/786478
.. [9] https://patchwork.ozlabs.org/project/openvswitch/patch/6aec0fb280f610a2083fbb6c61e251b1d237b21f.1576840560.git.lorenzo.bianconi@redhat.com/
.. [10] https://bugs.launchpad.net/neutron/+bug/1895972
.. [11] https://bugs.launchpad.net/neutron/+bug/1926515
.. [12] https://review.opendev.org/c/openstack/neutron/+/788594
.. [13] https://docs.openstack.org/neutron/latest/admin/config-dns-res.html
.. [4] https://specs.openstack.org/openstack/neutron-specs/specs/rocky/minimum-bandwidth-allocation-placement-api.html
.. [5] https://review.opendev.org/c/openstack/neutron/+/786478
.. [6] https://patchwork.ozlabs.org/project/openvswitch/patch/6aec0fb280f610a2083fbb6c61e251b1d237b21f.1576840560.git.lorenzo.bianconi@redhat.com/
.. [7] https://bugs.launchpad.net/neutron/+bug/1895972
.. [8] https://bugs.launchpad.net/neutron/+bug/1926515
.. [9] https://review.opendev.org/c/openstack/neutron/+/788594
.. [10] https://docs.openstack.org/neutron/latest/admin/config-dns-res.html

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@ -11,6 +11,7 @@
# under the License.
import collections
import copy
import re
import uuid
@ -131,10 +132,11 @@ SUPPORTED_DHCP_OPTS_MAPPING = {
'T1': 'T1',
'T2': 'T2',
'bootfile-name': 'bootfile_name',
'bootfile-name-alt': 'bootfile_name_alt',
'wpad': 'wpad',
'path-prefix': 'path_prefix',
'tftp-server-address': 'tftp_server_address',
'server-ip-address': 'tftp_server_address',
'server-ip-address': 'next_server',
'1': 'netmask',
'3': 'router',
'6': 'dns_server',
@ -175,10 +177,20 @@ SUPPORTED_DHCP_OPTS_MAPPING = {
'23': 'dns_server'},
}
# Baremetal specific DHCP options for VNIC_BAREMETAL ports
SUPPORTED_BM_DHCP_OPTS_MAPPING = copy.deepcopy(
SUPPORTED_DHCP_OPTS_MAPPING)
SUPPORTED_BM_DHCP_OPTS_MAPPING[4].update({
'tag:ipxe,bootfile-name': 'bootfile_name',
'tag:ipxe,67': 'bootfile_name',
'tag:!ipxe,bootfile-name': 'bootfile_name_alt',
'tag:!ipxe,67': 'bootfile_name_alt'})
# OVN string type DHCP options
OVN_STR_TYPE_DHCP_OPTS = [
'domain_name',
'bootfile_name',
'bootfile_name_alt',
'path_prefix',
'wpad',
'tftp_server']

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@ -139,6 +139,12 @@ def validate_port_extra_dhcp_opts(port):
:param port: A neutron port.
:returns: A PortExtraDHCPValidation object.
"""
# Get the right option mappings according to the port's vnic_type
vnic_type = port.get(portbindings.VNIC_TYPE, portbindings.VNIC_NORMAL)
mapping = constants.SUPPORTED_DHCP_OPTS_MAPPING
if vnic_type == portbindings.VNIC_BAREMETAL:
mapping = constants.SUPPORTED_BM_DHCP_OPTS_MAPPING
invalid = {const.IP_VERSION_4: [], const.IP_VERSION_6: []}
failed = False
for edo in port.get(edo_ext.EXTRADHCPOPTS, []):
@ -151,7 +157,7 @@ def validate_port_extra_dhcp_opts(port):
failed = False
break
if opt_name not in constants.SUPPORTED_DHCP_OPTS_MAPPING[ip_version]:
if opt_name not in mapping[ip_version]:
invalid[ip_version].append(opt_name)
failed = True
@ -171,14 +177,16 @@ def get_lsp_dhcp_opts(port, ip_version):
lsp_dhcp_disabled = False
lsp_dhcp_opts = {}
vnic_type = port.get(portbindings.VNIC_TYPE, portbindings.VNIC_NORMAL)
is_baremetal = vnic_type == portbindings.VNIC_BAREMETAL
# NOTE(lucasagomes): Baremetal does not yet work with OVN's built-in
# DHCP server, disable it for now
if (is_network_device_port(port) or
vnic_type == portbindings.VNIC_BAREMETAL):
if is_network_device_port(port):
lsp_dhcp_disabled = True
elif is_baremetal and ovn_conf.is_ovn_dhcp_disabled_for_baremetal():
lsp_dhcp_disabled = True
else:
mapping = constants.SUPPORTED_DHCP_OPTS_MAPPING[ip_version]
mapping = (constants.SUPPORTED_BM_DHCP_OPTS_MAPPING[ip_version]
if is_baremetal else
constants.SUPPORTED_DHCP_OPTS_MAPPING[ip_version])
for edo in port.get(edo_ext.EXTRADHCPOPTS, []):
if edo['ip_version'] != ip_version:
continue

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@ -207,6 +207,12 @@ ovn_opts = [
'or by checking the output of the following command: \n'
'ovs-appctl -t ovs-vswitchd dpif/show-dp-features '
'br-int | grep "Check pkt length action".')),
cfg.BoolOpt('disable_ovn_dhcp_for_baremetal_ports',
default=False,
help=_('Disable OVN\'s built-in DHCP for baremetal ports '
'(VNIC type "baremetal"). This alllow operators to '
'plug their own DHCP server of choice for PXE booting '
'baremetal nodes. Defaults to False.')),
]
@ -316,3 +322,7 @@ def is_ovn_emit_need_to_frag_enabled():
def is_igmp_snooping_enabled():
return cfg.CONF.OVS.igmp_snooping_enable
def is_ovn_dhcp_disabled_for_baremetal():
return cfg.CONF.ovn.disable_ovn_dhcp_for_baremetal_ports

View File

@ -20,6 +20,7 @@ import re
import threading
from futurist import periodics
from neutron_lib.api.definitions import portbindings
from neutron_lib.api.definitions import provider_net as pnet
from neutron_lib import constants as n_const
from neutron_lib import context as n_context
@ -730,6 +731,58 @@ class DBInconsistenciesPeriodics(SchemaAwarePeriodicsBase):
txn.add(cmd)
raise periodics.NeverAgain()
# A static spacing value is used here, but this method will only run
# once per lock due to the use of periodics.NeverAgain().
@periodics.periodic(spacing=600, run_immediately=True)
def check_baremetal_ports_dhcp_options(self):
"""Update baremetal ports DHCP options
Update baremetal ports DHCP options based on the
"disable_ovn_dhcp_for_baremetal_ports" configuration option.
"""
# If external ports is not supported stop running
# this periodic task
if not self._ovn_client.is_external_ports_supported():
raise periodics.NeverAgain()
if not self.has_lock:
return
context = n_context.get_admin_context()
ports = self._ovn_client._plugin.get_ports(
context,
filters={portbindings.VNIC_TYPE: portbindings.VNIC_BAREMETAL})
if not ports:
raise periodics.NeverAgain()
with self._nb_idl.transaction(check_error=True) as txn:
for port in ports:
lsp = self._nb_idl.lsp_get(port['id']).execute(
check_error=True)
if not lsp:
continue
update_dhcp = False
if ovn_conf.is_ovn_dhcp_disabled_for_baremetal():
if lsp.dhcpv4_options or lsp.dhcpv6_options:
update_dhcp = True
else:
if not lsp.dhcpv4_options and not lsp.dhcpv6_options:
update_dhcp = True
if update_dhcp:
port_info = self._ovn_client._get_port_options(port)
dhcpv4_options, dhcpv6_options = (
self._ovn_client.update_port_dhcp_options(
port_info, txn))
txn.add(self._nb_idl.set_lswitch_port(
lport_name=port['id'],
dhcpv4_options=dhcpv4_options,
dhcpv6_options=dhcpv6_options,
if_exists=False))
raise periodics.NeverAgain()
class HashRingHealthCheckPeriodics(object):

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@ -446,6 +446,24 @@ class OVNClient(object):
return ha_ch_grp.uuid
def update_port_dhcp_options(self, port_info, txn):
dhcpv4_options = []
dhcpv6_options = []
if not port_info.dhcpv4_options:
dhcpv4_options = []
elif 'cmd' in port_info.dhcpv4_options:
dhcpv4_options = txn.add(port_info.dhcpv4_options['cmd'])
else:
dhcpv4_options = [port_info.dhcpv4_options['uuid']]
if not port_info.dhcpv6_options:
dhcpv6_options = []
elif 'cmd' in port_info.dhcpv6_options:
dhcpv6_options = txn.add(port_info.dhcpv6_options['cmd'])
else:
dhcpv6_options = [port_info.dhcpv6_options['uuid']]
return (dhcpv4_options, dhcpv6_options)
def create_port(self, context, port):
if utils.is_lsp_ignored(port):
return
@ -476,18 +494,8 @@ class OVNClient(object):
'Logical_Switch', 'name', lswitch_name)
with self._nb_idl.transaction(check_error=True) as txn:
if not port_info.dhcpv4_options:
dhcpv4_options = []
elif 'cmd' in port_info.dhcpv4_options:
dhcpv4_options = txn.add(port_info.dhcpv4_options['cmd'])
else:
dhcpv4_options = [port_info.dhcpv4_options['uuid']]
if not port_info.dhcpv6_options:
dhcpv6_options = []
elif 'cmd' in port_info.dhcpv6_options:
dhcpv6_options = txn.add(port_info.dhcpv6_options['cmd'])
else:
dhcpv6_options = [port_info.dhcpv6_options['uuid']]
dhcpv4_options, dhcpv6_options = self.update_port_dhcp_options(
port_info, txn=txn)
# The lport_name *must* be neutron port['id']. It must match the
# iface-id set in the Interfaces table of the Open_vSwitch
# database which nova sets to be the port ID.
@ -606,18 +614,9 @@ class OVNClient(object):
else:
columns_dict['type'] = port_info.type
columns_dict['addresses'] = port_info.addresses
if not port_info.dhcpv4_options:
dhcpv4_options = []
elif 'cmd' in port_info.dhcpv4_options:
dhcpv4_options = txn.add(port_info.dhcpv4_options['cmd'])
else:
dhcpv4_options = [port_info.dhcpv4_options['uuid']]
if not port_info.dhcpv6_options:
dhcpv6_options = []
elif 'cmd' in port_info.dhcpv6_options:
dhcpv6_options = txn.add(port_info.dhcpv6_options['cmd'])
else:
dhcpv6_options = [port_info.dhcpv6_options['uuid']]
dhcpv4_options, dhcpv6_options = self.update_port_dhcp_options(
port_info, txn=txn)
if self.is_metadata_port(port):
context = n_context.get_admin_context()

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@ -281,6 +281,10 @@ class TestGateWayChassisValidity(base.BaseTestCase):
class TestDHCPUtils(base.BaseTestCase):
def setUp(self):
ovn_conf.register_opts()
super(TestDHCPUtils, self).setUp()
def test_validate_port_extra_dhcp_opts_empty(self):
port = {edo_ext.EXTRADHCPOPTS: []}
result = utils.validate_port_extra_dhcp_opts(port)
@ -384,11 +388,49 @@ class TestDHCPUtils(base.BaseTestCase):
dhcp_disabled, options = utils.get_lsp_dhcp_opts(port, 4)
self.assertFalse(dhcp_disabled)
# Assert the names got translated to their OVN names
expected_options = {'tftp_server_address': '10.0.0.1',
expected_options = {'next_server': '10.0.0.1',
'ntp_server': '10.0.2.1',
'bootfile_name': '"homer_simpson.bin"'}
self.assertEqual(expected_options, options)
def test_get_lsp_dhcp_opts_for_baremetal(self):
opt0 = {'opt_name': 'tag:ipxe,bootfile-name',
'opt_value': 'http://172.7.27.29/ipxe',
'ip_version': 4}
opt1 = {'opt_name': 'tag:!ipxe,bootfile-name',
'opt_value': 'undionly.kpxe',
'ip_version': 4}
opt2 = {'opt_name': 'tftp-server',
'opt_value': '"172.7.27.29"',
'ip_version': 4}
port = {portbindings.VNIC_TYPE: portbindings.VNIC_BAREMETAL,
edo_ext.EXTRADHCPOPTS: [opt0, opt1, opt2]}
dhcp_disabled, options = utils.get_lsp_dhcp_opts(port, 4)
self.assertFalse(dhcp_disabled)
# Assert the names got translated to their OVN names and the
# options that weren't double-quoted are now double-quoted
expected_options = {'tftp_server': '"172.7.27.29"',
'bootfile_name': '"http://172.7.27.29/ipxe"',
'bootfile_name_alt': '"undionly.kpxe"'}
self.assertEqual(expected_options, options)
def test_get_lsp_dhcp_opts_dhcp_disabled_for_baremetal(self):
cfg.CONF.set_override(
'disable_ovn_dhcp_for_baremetal_ports', True, group='ovn')
opt = {'opt_name': 'tag:ipxe,bootfile-name',
'opt_value': 'http://172.7.27.29/ipxe',
'ip_version': 4}
port = {portbindings.VNIC_TYPE: portbindings.VNIC_BAREMETAL,
edo_ext.EXTRADHCPOPTS: [opt]}
dhcp_disabled, options = utils.get_lsp_dhcp_opts(port, 4)
# Assert DHCP is disabled for this port
self.assertTrue(dhcp_disabled)
# Assert no options were passed
self.assertEqual({}, options)
class TestConnectionConfigToTargetString(base.BaseTestCase):

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@ -616,3 +616,73 @@ class TestDBInconsistenciesPeriodics(testlib_api.SqlTestCaseLight,
expected_calls = [mock.call('Logical_Router', lr0.uuid,
('external_ids', ext_ids))]
nb_idl.db_set.assert_has_calls(expected_calls)
def _test_check_baremetal_ports_dhcp_options(self, dhcp_disabled=False):
cfg.CONF.set_override('disable_ovn_dhcp_for_baremetal_ports',
dhcp_disabled, group='ovn')
self.fake_ovn_client.is_external_ports_supported.return_value = True
nb_idl = self.fake_ovn_client._nb_idl
self.fake_ovn_client._get_port_options.return_value = 'fake-port-opts'
port0 = {'id': 'port0'}
port1 = {'id': 'port1'}
port2 = {'id': 'port2'}
port3 = {'id': 'port3'}
self.fake_ovn_client._plugin.get_ports.return_value = [
port0, port1, port2, port3]
lsp0 = fakes.FakeOvsdbRow.create_one_ovsdb_row(
attrs={'type': constants.LSP_TYPE_EXTERNAL,
'name': 'lsp0',
'dhcpv4_options': ['fake-uuid'],
'dhcpv6_options': []})
lsp1 = fakes.FakeOvsdbRow.create_one_ovsdb_row(
attrs={'type': constants.LSP_TYPE_EXTERNAL,
'name': 'lsp1',
'dhcpv4_options': [],
'dhcpv6_options': []})
lsp2 = fakes.FakeOvsdbRow.create_one_ovsdb_row(
attrs={'type': constants.LSP_TYPE_EXTERNAL,
'name': 'lsp2',
'dhcpv4_options': [],
'dhcpv6_options': ['fake-uuid']})
lsp3 = fakes.FakeOvsdbRow.create_one_ovsdb_row(
attrs={'type': constants.LSP_TYPE_EXTERNAL,
'name': 'lsp3',
'dhcpv4_options': ['fake-uuid'],
'dhcpv6_options': ['fake-uuid']})
nb_idl.lsp_get.return_value.execute.side_effect = [
lsp0, lsp1, lsp2, lsp3]
self.fake_ovn_client.update_port_dhcp_options.side_effect = [
(lsp0.dhcpv4_options, lsp0.dhcpv6_options),
(lsp1.dhcpv4_options, lsp1.dhcpv6_options),
(lsp2.dhcpv4_options, lsp2.dhcpv6_options),
(lsp3.dhcpv4_options, lsp3.dhcpv6_options)]
self.assertRaises(periodics.NeverAgain,
self.periodic.check_baremetal_ports_dhcp_options)
def test_check_baremetal_ports_dhcp_options(self):
self._test_check_baremetal_ports_dhcp_options()
self.fake_ovn_client._nb_idl.set_lswitch_port.assert_called_once_with(
lport_name='port1', dhcpv4_options=['fake-uuid'],
dhcpv6_options=[], if_exists=False)
def test_check_baremetal_ports_dhcp_options_dhcp_disabled(self):
self._test_check_baremetal_ports_dhcp_options(dhcp_disabled=True)
expected_calls = [
mock.call(lport_name='port0',
dhcpv4_options=['fake-uuid'],
dhcpv6_options=[], if_exists=False),
mock.call(lport_name='port2',
dhcpv4_options=[],
dhcpv6_options=[], if_exists=False),
mock.call(lport_name='port3',
dhcpv4_options=[],
dhcpv6_options=['fake-uuid'], if_exists=False)]
self.fake_ovn_client._nb_idl.set_lswitch_port.assert_has_calls(
expected_calls)

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@ -0,0 +1,14 @@
---
features:
- |
Support for baremetal provisioning using OVN's built-in DHCP server
has been added for IPv4.
upgrade:
- |
A new configuration option called
``[ovn]/disable_ovn_dhcp_for_baremetal_ports`` has been added to
ML2/OVN for IPv4. Since PXE booting nodes can be very sensitive
depending on the hardware and some operators may prefer to use a
fully-fledged DHCP server instead of OVN's DHCP server this option
allows for disabling OVN's built-in DHCP server for baremetal ports
(vnic type "baremetal") when set to True. It defaults to False.